Contamination control and elimination is an important facet of cell culture efforts. Unwanted bacterial, viral or spore populations can easily ruin cell-based experiments common in biological and pharmaceutical research, and these populations can sometimes be notoriously difficult to detect and eliminate. Three principal methods of decontamination or sterilization have been used over the last century: dry heat, moist heat, and chemical.
Dry heat sterilization generally involves subjecting potentially contaminated items to a temperature of 120-160° C. for a period of one to two hours, at low relative humidity. This method of sterilization is effective at sterilizing items with good heat conductivity, such as metal parts, glassware, and the like.
Moist heat sterilization, on the other hand, can be performed in 20-30 minutes at a somewhat lower temperature than dry heat sterilization. However, it also requires steam and a pressure of 15-20 psi. This method was quickly adopted by hospitals because the pressurized steam penetrates wrapped instruments and packaged items much more quickly than dry heat.
The third method of decontamination involves spraying or wiping toxic chemicals onto potentially contaminated surfaces. This method is generally reserved for decontamination of items that are too large to put into a sterilization oven, or that contain sensitive electronics or other equipment that cannot survive a heat sterilization cycle.
Incubators have been used in cell culture and other laboratory applications for many years. More recently, automated incubators have been developed for use in automated laboratory robotic systems. Objects to be incubated (e.g., microtiter plates), instead of being placed in the incubator by hand, are handed off to a nest somewhere on the external surface of the automated incubator by a robot, upon which the incubator's automated object handling mechanism will move the object inside the incubation chamber to an unoccupied storage location. Reversing these steps causes the incubator to output the given object and present it to the robot.
Historically, both automated and non-automated (manual) incubators have been decontaminated by a combination of methods. Some laboratories may sterilize objects that can be removed from the internal chamber of the incubator, such as racks, shelves, or stackers, and autoclave (moist heat) or dry heat sterilize these pieces. Then, the internal surfaces of the incubator itself may be wiped down with toxic chemicals. Such a process is time-consuming, and the use of contamination-killing chemicals poses a certain danger to personnel and is avoided when possible.
Although cell incubators typically reach a maximum possible temperature of 50° C., some manual incubators use higher temperatures (130-160° C.) in order to sterilize the internal incubation chamber with a dry heat method. This, however, has not been possible in automated incubators, because the mechanics and electronics associated with the automated object movers inside the internal incubation chamber could not withstand high temperatures.